Well, believe what you want in the normalcy bias. But I am convinced that specific chatter put them on alert, but they didn’t want the public to know ... never let a crisis go to waste don’tchaknow. They want the crisis, to exploit it like they ALWAYS do. to take away more of your freedoms.
If “they” had them there as a result of specific information and failed to stop the attack then “they” are incompetent.
Therefore they will never admit they had specific chatter.